23 / 68
COVER STORY
June 2015
MODERN MINING
21
provided a safer alternative during the devel-
opment of Brakfontein ventilation shafts 2EO
and 6W1.
One option is to first excavate to the rock
level, construct a concrete shaft, which in the
case of Shaft 2EO would have been 20 m in
height and then back-fill to return to ground
level. This is a time consuming and expensive
undertaking.
Using the precast ring system to form the
shaft, MK Africa, was able to back-fill incre-
mentally, which halved the time it would have
taken using conventional methods.
MK Africa’s project scope entailed bulk
excavation and stockpiling of 113 000 m³ of
material to form the boxcut; and 170 m³ of
reinforced concrete for the vent bases. Precast
concrete rings of 4,5 m diameter were used for
Shaft 2EO; and 6,1 m diameter precast concrete
rings to a height of 10 m for Shaft 6W1. The
final phase entailed backfilling and compaction
of the boxcut to a total of 113 000 m³.
MK Africa has used the same technique
successfully on other projects, including
Brakfontein ventilation shaft 2B4 at Bokoni.
This involved the construction of a 38 m deep
ventilation shaft.
“This is an example of how we think ‘out-
side the box’ to add value for our clients. The
simplest solutions are frequently the best,”
points out Venter.
Modikwa No 2 shaft project
A current example is an approximately
11-month bulk infrastructure contract, sched-
uled for completion in June 2015 at Modikwa
platinum mine, which is located some 15 km
north-west of Burgersfort.
The scope of work here has been multi-fac-
eted and includes the construction of terraces
entailing approximately 400 000 m³ of fill mate-
rial to create the final 3 ha platform. The mine’s
new No 2 decline shaft goes into the mountain
at that level.
Also included was the upgrading of a 5 km
gravel access road, together with the installa-
tion of stormwater systems, the building of four
pollution control dams, and the construction of
a ventilation shaft.
Approximately 140 000 m³ of G5 material
was sourced from the existing mine waste
stockpile, with MK Africa carrying out screen-
ing operations on site. Here MK Africa’s
Cat 938K has been the primary loading tool.
This G5 material was used as overlay for the
road reconstruction, as well as for final terrace
surfacing.
Previous work at the mine has entailed bulk
earthworks and civils at Modikwa South 2.
The scope here involved 39 706 m³ of earth-
works; 1 150 m of precast pipe installation; and
283 413 m³ of terrace layer works.
Presently, MK Africa works on a maximum
of three to five contracts in parallel in order to
retain tight management control. “Our goal is
to keep growing to the point that we become
the employer of choice in our niche market, as
we expand MK Africa’s construction footprint
within the Southern African region.
“Whilst the industry is generally under
pressure at present, we at MK Africa have
a reasonable pipeline of work for the near
future and are exploring excellent prospects in
the medium term with our ‘partners’ in both
the mining and industrial sphere,” adds van
Schalkwyk.
Approximately 140 000 m³
of G5 material was sourced
from the existing waste
stockpile at Modikwa dur-
ing MK Africa’s recent bulk
infrastructure contract at
the mine.